Shane Tara, owner of the Colorado Patient Coalition in Federal Heights, waters medical-marijuana plants at her facility. Activists who worked for legalization of recreational cannabis in Colorado have created a model for other states.

COLORADO SPRINGS — Some call it the "Green Rush," but like the 19th-century prospectors who inspired the pun, not everyone who flocked to El Paso County's burgeoning medical-marijuana industry struck it rich.

In fact, most struck out.

Three years after a statewide medical marijuana boom brought scores of dispensaries to Colorado Springs, their ranks here have dwindled by half, city licensing figures show — culled by steep financial barriers, strict regulations at the state and local levels and the standard perils of being a small-business owner.